if the company that performed the "reload" of the Aircon system did their job right they would have understood the following. If you have a leak you need to track it down and not just refill it.
If there is a leak it is difficult to find given we are playing with gasses. They would therefore put a colour dye in the mix to allow it to be tracked the second time around. This time if the coolant gas is escaping you have a better chance of understanding where as the dye should accumulate around the leak. This can then be used to track the problem. It does rely on open access to the entire system and so removal of the bonnet and wings.
So ask them if they did add the dye and if not then why not ?
